Background: Through the development of robust techniques and their comprehensive validation, cardiac magnetic resonance imaging (CMR) has developed a wide range of indications in its almost 25 years of clinical use. The recording of cardiac volumes and systolic ventricular function as well as the characterization of focal myocardial scars are now part of standard CMR imaging. Recently, the introduction of accelerated image acquisition technologies, the new imaging methods of myocardial T1 and T2 mapping and 4-D flow measurements, and the new post-processing technique of myocardial feature tracking have gained relevance. Method: This overview is based on a comprehensive literature search in the PubMed database on new CMR techniques and their clinical application. Results and conclusion: This article provides an overview of the latest technical developments in the field of CMR and their possible applications based on the most important clinical questions.
Problem: in recent years, new studies have been published on biological effects of strong static magnetic fields and on thermal effects of high-frequency electromagnetic fields as used in magnetic resonance imaging (MRI). Many of these studies have not yet been incorporated into current safety recommendations. Method: scientific publications from 2010 onwards on the biological effects of static and electromagnetic fields of MRI were searched and evaluated. Results: new studies confirm older work that has already described effects of static magnetic fields on sensory organs and the central nervous system accompanied by sensory perception. A new result is the direct effect of Lorentz forces on ionic currents in the semicircular canals of the vestibular organ. Recent studies on thermal effects of radiofrequency fields focused on the development of anatomically realistic body models and more accurate simulation of exposure scenarios. Recommendation for practice: strong static magnetic fields can cause unpleasant perceptions, especially dizziness. In addition, they can impair the performance of the medical personnel and thus potentially endanger patient safety. As a precaution, medical personnel should move slowly in the field gradient. High-frequency electromagnetic fields cause tissues and organs to heat up in patients. This must be taken into account in particular for patients with impaired thermoregulation as well as for pregnant women and newborns; exposure in these cases must be kept as low as possible.
Objective: To evaluate the radiographic characteristics of dentigerous cysts (DC) diagnosed at the School of Stomatology of the Universidad Peruana Cayetano Heredia (UPCH) during the period of 2010–2017. Material and methods: Retrospective, descriptive, observational and cross-sectional study, where the panoramic radiographs of 37 cases of DC were selected. Results: The total number of diagnosed cases of dentigerous cysts was 233, which after inclusion and exclusion criteria, 37 cases were obtained, of which 45.9% of cysts were found in the second decade of life with a higher frequency of 51.4 percent for women, and a jaw predilection of 59.5% in all cases. In addition, it was found that 97.3% of the cases were radiolucent, defined limits were found in 67.6%, corticalized edges in 54.1% and unilocular in 94.6%. All dentigerous cysts were associated with a tooth, of which closed apex (48.6%) and tooth displacement (59.5%) were observed. The adjacent tooth was not affected in 56.8% of cases, but its hard lamina was affected (59.5%). The 68.2% of cases did not affect the basal mandibular cortex, but did displace the inferior dental canal (54.5%) and 46.7% of cases displaced the floor of the maxillary sinus. Conclusions: Most of the results obtained on the characteristics in the Peruvian population support previous studies reported in America, Europe and Asia. Radiographically the dentigerous cyst showed characteristics that support its clearly benign behavior.
In the process of X-ray transmission imaging, the mutual occlusion between structures will lead to the image information overlap, and the computed tomography (CT) method is often required to obtain the structure information at different depths, but with low efficiency. To address these problems, an X-ray focused on imaging algorithm based on multi-line scanning is proposed, which only requires the scene target to pass through the detection area along a straight line to extract multi-view information, and uses the optical field reconstruction theory to achieve the de-obscured reconstruction of the structure at a specified depth with high real-time. The results of multi-line scan and X-ray reconstruction of the target show that the proposed method can reconstruct the information of any specified depth layer, and it can perform fast imaging detection of the mutually occluded target structures and improve the recognition of the occluded targets, which has a good application prospect.
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